The present invention relates to a method of and a device for estimating motion in a sequence of pictures. Such a method is essentially applicable in the field of digital signal processing, for information compression, picture quality improvement, target tracking, etc. and, for example, in digital picture coding devices for the reduction of the rate of information to be transmitted or to be registered when, for example, magnetoscopes are concerned.
The Article by A. N. Netravali and J. D. Robbins "Motion-compensated Television coding: Part I" published in the magazine "The Bell System Technical Journal", Vol. 58, No. 3, March 1979 describes a motion estimation method providing essentially for performing a classification of picture elements in fixed elements and moving elements and for estimating the motions by means of an adaptive prediction method utilizing elements of a preceding picture for comparing them in position and luminosity with those of the current picture. In this method of estimating motion element by element, known under the name of pel-recursive method, a displacement vector is associated with each picture element such that the difference between two successive pictures has a minimum energy, whilst taking the estimated motions into account, the minimization being effected in this case by means of the Newton-Raphson method.
The Article by C. Cafforio and F. Rocca "Methods for measuring small displacement of television images" published in the magazine "IEEE Transactions on Information Theory", IT-22, September 1976, pp. 573-579 also utilizes this principal, but operates with a block of elements and attributes the same displacement vector to all the elements of a block. The method described in this Article has, however, the drawback that the correlation between the neighbouring blocks is not taken into account.